Latching mechanism



Jan. 17, J B. MacNElLL r AL LATCHING MECHAN I SM Filed May 14, 1956 3 Sheets-Sheet l I I LLAJ LLU WITNESSES: lNVENTORS CW John B. MacNe/Y/rfi John 14 May g? BY j a '2 ATTORN Jan. 17, 1939. J. B MacNElLL Er AL 2,144,502

LATCHING MECHANISM Filed May 14, 1936 3 Sheets-Sheet 2 John B. W2'5'35253/ & v. g John W May ATTORN Jan. 17, 1939. J. B. Ma NElLL ET AL 2,144,502

LATCHING MECHANISM Filed May 14, 1936 3 SheetsSheet 3 WITNESSES: INVENTORS Jahn B. MQCN8///&

John 14/. May

ATTORNE Patented; Jan. 17, 1939 PATENT OFFICE 3,144,502 LATCHING MECHANISM John B. hhcNeiil, Wilkinsburg, and John W.

May Forest Hills, Pa., assignors to Westinghouse Electric 1;

Manufacturing Company,

East Pittsburgh, Pa., a corporation of Pennsylvania Application my 14, 1936, Serial No. 79,670

14 Olllml. (Cl- 200-109) This invention relates to latching mechanisms for circuit interrupters.

In circuit interrupters, the operating mechanism for actuating the contact members through a switching operation is usually held in a biased position by means of a latching mechanism to maintain the contact members in a contact making position. The latching mechanism is operative to release the actuating mechanism upon the occurrence of predetermined electrical conditions to cause the actuation of the contact members to an open circuit position.

In order to retain the actuating mechanism in a closed circuit position, the latching mechanism usually consists of heavy complicated linkages designed to withstand the reactive pressures exerted by the actuating mechanism when in closed position. Because of the complicated design of the latching mechanism and the large mass of parts which must be moved when the latch is tripped, the tripping movement is not transmitted to the actuating mechanism until three or more cycles after the tripping movement is initiated. This slowness in effecting the tripping sometimes results in damage to valuable apparatus connected in the circuit designed to be protected by the circuit interrupter.

An object of this invention is to provide a quick acting latching mechanism for a circuit interrupter to obtain high speed operation.

Another object of this invention is to provide a latching mechanism for a circuit interrupter, the members of which are independently mounted and. are disposed for small angular movement to obtain high speed operations.

This invention accordingly is disclosed in the embodiment thereof shown in the accompanying drawings and comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth and the scope of the application of which will be indicated in the appended claims.

For a fuller understanding of the nature and objects of the invention, reference may be had to the following detailed description, when taken in conjunction with the accompanying drawings, in which:

Figure 1 is a view, partly in side elevation and partly in section, illustrating the latching mechanism of this invention as applied to the operating mechanism of a circuit interrupter;

Fig. 2 is a plan view of the latching mechanism in conjunction with the trip-free elements of the actuating mechanism of a circuit interrupter;

Figs. 5 and 6 are side elevational views of a portion of the operating mechanism shown in Fig.

1 illustrating the position of the trip-free elements of the circuit interrupter.

Referring to the drawings, and Fig. 1 in particular, the latching mechanism ill of this invention 10 is shown carried on the frame 12 of the operating mechanism for cooperating with the operating levers H to retain them in a closed circuit position.

As an example and in order to facilitate the u disclosure of this invention, a portion of the operating mechanism of one of the well known circuit interrupters is illustrated in detail in the drawings, it being understood that the latching mechanism of this invention may be employed with any of the trip-free circuit interrupters in which the operating mechanism and the contact members are normally biased to an open circuit position when in the closed circuit position.

The contact members and actuating levers (not shown) of the circuit interrupter are connected through an operating bar it to a lever II by means of a pin 20. The lever l8 carries a trip-free bar or roller 22 pivoted in one end of the lever and adapted to be engaged by the latching mechanism pivotally connected to a lever 24 by means of a pivot pin 26. The lever 24 is pivotally anchored to the frame l2 of the circuit interrupter by the pin 2!.

When in the closed circuit position,the lever 24 is biased for movement in a clockwise direction about its pivot point 28 by means of the retrieving spring 30 positioned between the lever 24 and the frame l2. One end of the spring 30 is securely anchored by means of the bracket 32 to the lever 24, while the other end of the spring abuts the frame i2 and may be maintained in that position by any suitable means.

A latch 34 is carried by the frame l2 and is biased by means of a spring 35 to engage the pin 26 linking the levers l8 and 24 to retain them in the position shown in full lines in Fig. 1. In order to cause the latch 34 to release the pin 26 during a tripping movement of the mechanism, the lever I8 carries a projection 36 on its end adjacent the pin 26 for contacting a projection 38 carried on the latch 34 when the lever I is rotated to a predetermined position about its pivot point 20. This causes the latch 34 to rotate in a clockwise direction about its pivot point 40.

When the latch 34 is rotated a predetermined distance, it releases the pivot pin 20, and the reactive force of the compressed spring 80 causes the lever 24 to rotate in a clockwise direction about its fixed pivot point 20 to the position shown in dotted lines in Fig. 1. During this movement of the lever 24, the lever I0 rotates about the pivot pin 20 In a clockwise direction to return the free end of the lever I0 to the position shown in Fig. 6 where the trip-free bar or roller 22 may be latched by the latching mechanism I0.

In order to actuate the mechanism to a closed circuit position, the lever 24 is pivotally connected to the armature 42 of an electromagnet 44 by means of a link 48. One end of the link 40 is pivotally connected to the lever 24 by a pin 40 and.

the other end is pivotally connected to the armature 42 of the electromagnet 44 by means of a pin When the electromagnet 44 is energised, the solenoid 42 and link 40 are actuated downwardly to rotate the levers I0 and It in a counterclockwise direction about the trip-free roller 22 and the pivot point 20 to the position shown in full lines in Fig. 1 of the drawings. In moving to this position, the pivot pin 20 is engaged by the latch 04 so that the levers I0 and 24 are retained in closed circuit position.

In the particular operating mechanism illustrated, the trip-free roller 22 is carried between two of the leversIl which are suitably braced by means ofa bar 52 therebetween. In order to provide a suitable pivot point 20 for the levers I8, two levers 24 are provided for supporting the pivot pin 26 and are held in spaced relation by means of the bar 54. The bar 04 further acts as a support for the links I0 to prevent excess movement of the levers I0 and to cause the roller 22 carried by the levers I0 to align with the pivot pin 20 when the levers 24 are in theposition shown in Fig. 6, or in fulllines in Fig. 1.

When the operating mechanism is in the closed circuit position shown in full lines in Fig. l, the

roller" is engaged by an L-shaped engaging lever or member 56. The engaging member I is pivotally carried on the frame I2 of the device by means of the pin 50 and is biased to an operative position by means of a spring 00 to engage the roller 22. The ends of the spring 00 are set into flat bottom cylindrical recesses or wells 62 and 64 in the'lever 50 and the frame I2. respectively.

In order to retain the lever 00 in its operative position to engage the roller 22, a lever 00 is provided for cooperatively engaging the lever I50. The lever 66 is pivotally mounted at one end to the frame I2 by means of the pin 00. The

other end of the lever it normally rests on the free end 51 of the lever 08 and carries a notch I0 for engaging the cooperating surface I2 on the engaging lever 58 to retain it in a latched position.

In order to insure the engagement of the lever 66 with the lever 56. the lever 06 is biased in a counterclockwise direction about the pin 00 by means of springs I4 and It. The spring I4 is suitably disposed between the lever 08 and a bracket I8 carried by the frame I2.

Since the biasing force of the springs 14 and It are not strong enough to retain the levers arcane:

00 and 00 in their operative position to retain the biased operating mechanism in a closed circuit position, a latch 00 is provided for latching the members in their engaging positions. The latch 00' is carried on one arm of a .bell crank 02 which is plvotally mounted to the frame by means of a pin 04. The latch 00 is normally biased to its latched position by the spring I0 which is carried between the lever 06 and the arm 03 of the bell crank" 02. In practice, the lever 00 is provided with a cutout portion 00 through which the arm of the bellcrank 02 carrying the latch 00 projects to engage the top of the lever 00.

In order to insure a positive movement of the lever 00 in a clockwise direction about its pivot point 00 to disengage the lever 06 during a tripping movement of the latching mechanism, a projection 00 is carried on the arm 00 of the bellcrank 82 for abutting a projection 00 carried on the under-surface of the lever 66.

The latch 00 carried by the bellcrank 02 may be actuated to disengage the lever 66 by means of a force applied to the arm 80 of the bellcrank to rotate it in a counterclockwise direction about the pin 04. The force may be applied to the arm 00 of the bellcrank by any suitable means. In practice, an electromagnet 00 is carried on the framework I2 of the device-and is adapted, when energized in response to predetermined electrical conditions, to actuate the solenoid 89 in an upward direction to strike the arm 03 and cause the latch 00 to release the lever 68.

As shown in Figs. 8 and 4, the solenoid 00 is also adapted to be actuated manually through the use of a lever 02 pivotally carried on the frame I2 by the pin 04. The lever 82 may comprise two parallel bars suitably fastened together and presenting a forked end 00 at one end thereof. In order to guidethe lever 02 when it is actuated, a bolt I00 is so carried on the frame I2 that it extends in an upward direction in the opening of the forked end 80 of the lever 02. An intermediate member 00 is loosely seated on the end of the bolt I00 between the guides I02 carried'on the frame and is adapted to be so moved when the lever 02 is actuated as to actuate the solenoid 00 to strike the bell crank 02 and trip the latching mechanism. The lever 02 is normally biased to its inoperative position by means of a spring 08 suitably mounted-between the lever and the frame I2. 7

A means is provided for preventing resetting of the latches after their release, until the roller 22 has been returned to its predetermined latched position. This means comprises a retrieving pawl I04 which is pivotally mounted on the frame I2 by means of a pin I00. The end I00 of the pawl is provided with a sliding contact surface I00 which is adapted to be engaged by the roller 22 as it is moved to latching position. 'The pawl I04 is normally biased in a clockwise direction about its pivot pin I00 by means of a spring IIO suitably mounted between the frame I2 and the end I00 of the pawl.

The spring IIO which biases the pawl I04 in a clockwise direction about the pin I06 is stronger than the spring 80 which biases the engaging lever II in a counterclockwise direction about its pivot point 00, so that as the roller 22 moves to its unlatched or open circuit position, the pawl I04 rotates and forces the engaging member 00 to rotate in a clockwise direction into engagement with a resilient stop or bumper II2 suitably mounted on the frame I2. In this position, the lever 88 is inoperative to engage the trip tree bar or roller 22 to retain it in a latched position.

In operation, the roller 22 may be released from the latched position shown in Fig. 3 to release the operating mechanism by actuating the solenoid 88 to strike the arm 88 of the bellcrank 82. The solenoid may be actuated in response to the energization of the electromagnet 88 upon the occurrence of predetermined conditions or in response to a movement of the manually operated lever 82 to force the bar 88 and the solenoid 89 into engagement with the arm 88 of bellcrank 82 to rotate it in a counterclockwise direction about its pivot point 84. When the bellcrank 82 is rotated, the latch 88 is moved out of engagement with the lever 88 and at the same time the projection 88 carried on the arm 88 strikes the projection 88 carried by the lever 88 and causes a positive rotation of the lever 88 in a clockwise direction about its pivot pin 88.

The clockwise movement of the lever 88 about its pivot point causes the notched end I8 of the lever 88 to release the L-shaperl engaging member 88. Since the reactive pressures of the biased actuating mechanism acting through the trip-free roller 22 are greater than the biasing force of spring 88, the engaging member 88 rotates in a clockwise direction about its pivot point 58 to disengage the roller 22.

When the roller 22 is disengaged, the lever I8 rotates in a counterclockwise direction about its pivot point 28 to the position shown by the dotted lines in Fig. 1 or as illustrated in Fig. 5. During this movement of lever I8, the roller 22 clears the sliding contact surface I88 of the pawl I84 and the pawl is biased by means of the spring III) in a clockwise direction about its pivot point I 88 to contact the L-shaped engaging member 58. Since the spring H8 is stronger than the spring 88, the pawl exerts a pressure against the engaging member 88 sufllcient to cause the engaging member to rotate in a clockwise direction about its pivot point 58 to a position where the engaging member 58 is inoperative for retaining the roller 22.

As the lever I8 moves to the unlatched position shown in dotted lines in Fig. 1, or as shown in Fig. 5, the projection 88 on the end of the lever I8 contacts the projection 88 on the latch 84 and causes the latch to rotate in a clockwise direction about its pivot point 48 to release the pivot pin 28. When the latch 84 releases the pin 28, the spring 88 forces the links 24 to the position shown in dotted lines in Fig. 1 and as shown in Fig. 6. Since the lengths of the lever arms between the pivot pins 28 and 28, and 28 and 28 are fixed, the movement of the levers 24 to the position shown in Fig. 6 causes the lever arms I8 to rotate in a clockwise direction to a position where the roller 22 carried by the levers I8 is in its latched position in alignment with the fixed pivot point 28.

As the roller 22 approaches its latched position, it engages the sliding contact surface I88 of the pawl I84 and causes it to rotate in a counterclockwise direction about its pivot point gaging position, the top surface 81 of the lever 88 slides along the under-surface 81 oi the lever 88 to a position where the notch 18 of the lever 88"engages the cooperative surface I2- of the L-shaped engaging member 88 to retain the'lever 88 in its engagingposition with the roller 22.

The movement of the lever 88 into its engaging position with the L-shaped member 88 causes the latch 88 of the bellcrank 82 to lock the lever 88 in its engaging position with the lever since the bellcrank 82 is biased to its latched position by means of the spring 18. .When the latching mechanism is in this position, the roller 22 is retained in its latched position in alignment with the pivot pin 28 of the links 24.

In order to actuate the circuit interrupter to a closed position. the electromagnet 44 may be energized in any of the well known manners to actuate the solenoid 42 and pull down on the levers I8 and 24 to cause them to rotate in a counterclockwise direction about their concentric pivot points 22 and 28. When actuated in this manner, the levers I8 and 24 are returned to the closed circuit position where the pivot pin 28 is engaged by the latch 84. Since the contact members (not shown) oi the circuit interrupter are actuated in response to a movement of the operating bar I8 which is pivotally linked to the lever I8, it is evident that a movement of the lever I8 to the position as described actuates the contact members to a circuit closing position.

The notches 88 and I8 on the bellcrank 82 and the lever 88, respectively, are very slight, being less than three thirty-seconds of an inch deep, so that when the bellcrank 82 is actuated to unlatch the lever 88, a slight movement of the bellcrank 82 and the lever.88 eirects a tripping of the engaging member 58 to release the roller 22. It is to be noted that the members of the latching mechanism are mounted on the frame independently of each other and are so disposed that when in the latched position they balance the reactive pressures exerted by the biased operating mechanism of the circuit breaker. Since it is only necessary to move the respective membersof the latching mechanism through a very small are to effect the release of the trip-free bar, it is evident that the mass movement of the members will be small.

By arranging the members in this manner, it is possible to decrease the time in which a movement oi the trip-free roller to a tripped position is initiated to less than one-half a cycle from the time the tripping movement of the latching mechanism is initiated as compared to the period of time of some three to five cycles necessary where the latching mechanisms of the prior art are employed.

Although this invention has been described with reference to a particular modification thereof, it is, of course, to be understood that this invention is not to be limited. except insofar as is necessitated by the prior art and the scope of the appended claims.

We claim as our invention:

1. In a latching mechanism for a circuit interrupter provided with a member biased to an open circuit position for effecting a switching operation, in combination, means biased to releasably engage the member to restrain it in a predetermined position, a spring biased arm disposed for cooperative engagement with the bar engaging means to partially balance the reactive pressures from the biased member, a latch for locking the arm to lock the bar engaging means to retain the biased member in a predetermined position, said engaging means, said arm and said latch each having a relatively small mass and each disposed for a small amount of movement to provide for a high speed tripping operation.

2. In a latching mechanism for a circuit interrupter provided with an operating mechanism biased to an open circuit position for effecting a switching operation, the operating mechanism including a trip free bar, in combination, a spring biased means biased to engage the trip free bar to retain it in a predetermined position, a spring biased means disposed to maintain the spring biased retaining means in an inoperative position against its bias until the trip free bar is in a predetermined position, a spring biased arm disposed for cooperative engagement with the spring biased bar engaging means to retain the bar engaging means in its operative position engaging the trip free bar, a latch for locking the arm to lock the bar engaging means to retain the trip free bar in a predetermined position.

3. In a latching mechanism for a circuit interrupter provided with an operating mechanism biased to an open circuit position for effecting a switching operation, the operating mechanism including a trip free bar, in combination, means releasably engaging the trip free bar to retain it in a predetermined position, a spring biased arm disposed for cooperative engagement with the bar engaging means to partially balance the reactive pressures from the biased operating mechanism, a latch for locking the arm to lock the bar engaging means to retain the trip .i'ree bar in a predetermined position, means operable to trip the latch, and means carried on the latch for providing a positive movement of the arm to disengage the bar engaging means and permit it to move in response to the reactive pressures from the biased operating mechanism to release the trip free bar when the latch is tripped.

4. In a latching mechanism for a circuit interrupter provided with an operating mechanism biased to an open circuit position for effecting a switching operation, the operating mechanism including a trip free bar, in combination, means biased to reieasably engage the trip free bar to restrain it in a predetermined position, a spring biased arm disposed for cooperative engagement with the spring biased bar engaging means to partially balance the reactive pressures from the biased operating mechanism, a latch for locking the arm to lock the bar engaging means to retain the trip free bar in a predetermined position, and means operable to trip the latch to release the spring biased. arm from its cooperative engagement with the spring biased engaging means and permit the reactive pressures from the biased operating mechanism to actuate the engaging means to release the trip free bar.

5. In a latching mechanism for a circuit interrupter provided with an operating mechanism biased to an open circuit position for efiecting a switching operation, the operating mechanism including a trip free bar, in combination, means for releasably engaging the trip free bar to retain it in a predetermined position, a spring biased arm disposed for cooperative engagement with the bar engaging means to partially balance the reactive pressures from the biased operating mechanism, a latch for locking the arm to lock the bar engaging means to retain the trip free bar .in a predetermined position, means operable to trip the latch, and means carried on the latch adapted to exert a force on the spring biased arm during a tripping of the latch for providing a positive movement of the arm to disengage the bar engaging means and permit it tormove in re-.

operative to trip the engaging means to cause it to release the element of the operating mechanism and permit movement of the mechanism to the open circuit position, and means for biasing the engaging means to an inoperative position to retain the element until the element is returned to the predetermined position.

7. In a latching mechanism for a circuit interrupter provided with an operating mechanism including a plurality of elements biased to an open circuit position for effecting a switching operation, in combination, means for engaging one of said elements to retain the mechanism in a predetermined position, means biasing said engaging means to engaging position, means operative to trip the engaging means to release the element of the operating mechanism and permit movement of the mechanism to the .open circuit position, and means disposed to maintain the engaging means in an inoperative position to retain the element until the element is returned to the predetermined position.

8. In a latching mechanism for a circuit interrupter provided with an operating mechanism including a plurality of elements biased to an open circuit position for effecting a switching operation, in combination, means for engaging one of said elements to retain the mechanism in a predetermined position, means biasing said engaging means to engaging position when the mechanism is in said predetermined position, means operative to trip the spring biased engaging means to release the element oi the operating mechanism and permit movement of the mechanism to the open circuit position, and spring biased means disposed to maintain the spring biased engaging means in an inoperative position to retain the element until the element is returned to the predetermined position.

9. In a latching mechanism for a circuit breaker provided with an actuating member biased to open circuit position to etlect interruption or the circuit, a pivoted main latch biased to latching position for engaging and restraining said actuating member in a predetermined position, a pivoted spring biased arm having a narrow shoulder for engaging and restraining said main latch in latching position, a light load latch for engaging and locking said arm to lock said main latch in latching position, means for moving said light load latch to released position to effect release of said arm, said light load latch having means for positively engaging and moving said arm to release the same from its engagement with said main latch upon movement of said light load latch to released position,

10. In a latching mechanism for a circuit breaker provided with an actuating member biased to an open circuit position to effect a switching operation, in combination, a main latch biased to engage said member to restrain it in a predetermined position, a movable arm biased to enall gage said latch to partially balance the component of the biasing force tending to move said latch to releasing position, a latch for locking said arm to lock said main latch to restrain said actuating member in said predetermined position, said arm and latch having relatively small mass and being disposed for a small amount of movement to effect release of said member.

11. In a latching mechanism for a circuit breaker provided with an actuating member biased to open circuit position to effect a circuit opening operation, in combination, a main latch having a latching position for engaging said actuating member to restrain it in a predetermined position, means biasing said latch to latching position, a spring biased arm for engaging said latch in its latching position to partially balance the component of the biasing force on said member tending to move the latch to releasing position, a light load latch for locking said arm to lock said main latch in latching position, to restrain said actuating member, and means holding the main latch in an inoperative position until said actuating member reaches said predetermined position.

12. In a latching mechanism for a circuit breaker provided with an actuating member biased to open circuit position to effect Opening of the circuit, a pivoted main latch biased to a latching position for engaging and restraining said member in an inoperative position, a spring biased pivoted arm having a narrow latch surface for engaging and restraining said main latch in its latching position, a light load spring biased latch for locking said arm to lock said main latch in latching position, a spring biased pawl controlled by said actuating member for maintaining said main latch in released position to prevent resetting of said arm and light load latch until said actuating member is returned to said inoperative position following its release.

13. In a latching mechanism for a circuit breaker provided with an actuating member biased to open circuit position to effect interruption of the circuit, in combination, a main latch having a latching position for engaging said member to restrain it in inoperative position, means biasing said main latch to latching position, a spring biased arm for engaging said main latch to restrain it in latching position, a light load latch for locking said arm to lock said main latch in latching position, and a spring biased means controlled by said actuating member for holding said main latch in released position until said actuating member reaches said inoperative position.

14. In a latching mechanism for a circuit breaker provided with a spring biased actuating member releasable to efiect opening of the circuit, in combination, a main latch having a latching position for engaging and restraining said actuating member in a predetermined position, means biasing said latch to latching position, a spring biased arm for engaging and restraining said main latch in latching position, a spring biased light load latch for locking said arm to lock said main latch in latching position, means including a member controlled by said actuating member for maintaining said main latch in inoperative position until said actuating member is returned to said predetermined position following each release of the same.

JOHN B. MACNEILL. JOHN W. MAY. 

